CHANGELOG: Document the upcoming release 1.4.1

CHANGELOG: Move "Unreleased" to "1.4.0"

knigge: Update moduledoc to fix a reference to Application.put_env

Release 1.2.0: Replace the existence check with `mix knigge.verify`

For details please see https://hexdocs.pm/knigge/the-existence-check.html

Project: Bump version from 1.1.0 to 1.1.1

Release 1.1.0: Delegate at runtime in `test` per default

This release extends the `delegate_at` option to allow passing a list of
environments similar to `check_if_exists`.

To be more clear on the intent `delegate_at` has been renamed to
`delegate_at_runtime?` and `check_if_exists` to `check_if_exists?`. The
old names are still accepted by `Knigge` but a deprecation warning is
printed if they are being used.

With this done the default of `delegate_at_runtime?` has been set to
`[only: :test]` which allowed to change the default of
`check_if_exists?` to `true`.

Now `Knigge` will no longer generate compiler warnings in test when
using `Mox.defmock` since the implementation will - as the this change
suggests - be loaded at runtime instead of compile time.

Release 1.0.4: Fix `check_if_exists` env spec

As it turns out `Mix.env` always returns `:prod` for dependencies.
Knigge now determines the callers `env` and puts it into the `Options`
struct to use it instead of a static `@env` module attribute.

Also add a section on compiler warnings which happen in `:test` due to
the compiler not finding the module.

Release 1.0.3: Control existence check on an env basis

Knigge now only checks if the given modules exist based on the value of
the `check_if_exists` option, which accepts a number of values:

- a boolean to switch the existence check fully on or off
- an environment (atom) or list of environments (list of atoms)
- `only: <envs>` or `except: <envs>` (single value keyword list)

For more information see the docs.

Release 1.0.2: Fix a typo in Options

The typo made the usage of the `otp_app` option impossible and as it
turned out the covering test didn't run. Oops ...

Release 1.0.1: Fix a bug with multiple defdefaults for the same callback

Only the first defdefault for a callback was used during generation;
now all defdefaults are being used to generated function clauses.